It's easier to get Apache to log client IP addresses utilizing X-Forwarded-For Headers than it is using IIS. By default, the logs do not record source IP addresses for clients - but as of Apache version 2.4 you can use the ErrorLogFormat directive in the httpd.conf file as explained below. ->Did you want to learn about XFF on IIS ? There’s been a lot of debate here in the office about how best to capture both your Loadbalancer’s IP and the Source IP of the user in your access_log in Apache 2.4 . This is the tried and tested method we've come up with. How to log X-Forwarded For Headers using Apache 2.4 CentOS 7 When you start out, your httpd.conf will look something like this: LogFormat "%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\"" combined LogFormat "%h %l %u %t \"%r\" %>s %b" common CustomLog "logs/access_log" combined Now the %h is already there to capture your header, which...